This show is pretty neat. I've watched three episodes. Revolves around Shawshank Prison in the town of Castle Rock.

Basically, the former warden of the jail killed himself. After he was found, they found a boy (Bill Skarsgard), trapped in a cage, not a cell, a cage in an abandoned part of the jail. Before the warden killed himself, he told the boy to ask for Henry Deaver, a former townie turned lawyer who represents death row inmates. The Jail tries to keep him a secret, but one of the guards (Ginger gallagher's first boyfriend from Shameless), tips him off.

It's coming to light that the boy might be the literal devil, and letting him out will start bad things happening all over the town.